1. Field
The present disclosure relates to a resonator, and more particularly, to a resonator installed at the rear of a turbo charger of a vehicle and combined with a Helmholtz resonator and a groove type resonator to attenuate both high-frequency noise and low-frequency noise.
2. Description of the Related Art
An inhaling system of a vehicle for the combustion of a fuel introduces air into an engine while subsequently passing through a snorkel, a first resonator, an air filter, a turbo charger, a second resonator, an intercooler, a duct and an engine manifold.
While air is inhaled, there are generated a pulsation noise which is a noise of fluid caused by opening or closing an inhaling or exhausting valve and an air current noise which is a noise of turbulence caused by the vortex or collision when a high-speed exhaust gas current passes through a silencer.
Noise is a sound in an audible frequency (16 Hz to 20 kHz) which is sensuously not desired by persons, among sonic waves generated by vibration of the air. The sonic wave is generated by very small displacement of each air particle which repeatedly vibrates in an equivalent location like a pendulum.
For ensuring convenient feeling of a driver and safe driving, it is necessary to reduce the noise. The first resonator and the second resonator are used for reducing noise.
A Helmholtz resonator is widely used for reducing sound. The Helmholtz resonator includes a neck and a resonance chamber with a predetermined capacity. The Helmholtz resonator is attached to a certain duct to decrease a sound with a specific inherent frequency.
As techniques using the Helmholtz resonator, Korean Patent Publication No. 1999-0049960 discloses a volume-variable Helmholtz resonator, and Korean Patent Publication No. 2009-0047083 discloses a series Helmholtz resonator. These techniques however have a limit in that only a noise within a limited frequency band can be attenuated.
In addition, Korean Utility Model Publication No. 1998-033640 discloses that an interfering silencer for attenuating a high-frequency noise is provided at the front of a resonator for attenuating a low-frequency noise in order to attenuate both of the low-frequency and high-frequency noises.
However, this structure is suitable for the first resonator which is installed at the rear of the snorkel, and the interfering silencer has an interfering range of 3 kHz or below. In addition, the interfering principle is a ½ or ¼ wavelength duct principle (length-change principle). Here, if the frequency of the noise range increases further, the interfering silencer may not be used appropriately, and therefore this structure is not suitable for the second resonator into which air is rapidly introduced by the turbo charger. Further, the inner structure of the interfering silencer has a lattice plate and a chamber, its volume becomes great.